This recipe yields three spiders. Replacing the Sapphire with a Flawless Sapphire will yield six spiders. In addition, after crafting the spiders, one of the following recipe notes is added to the inventory:

As most locations where the pods can be obtained do not respawn, it can become difficult to obtain more if the initial supply runs out. There is, however, a single respawning spider pod available on Solstheim just south of Bloodskal Barrow, near the Shrine of Kynareth, which you can use to make more cloaked spider scrolls.

Cloaked spiders do not despawn and only disappear when killed, which makes them an effective weapon, which behaves similar to a summoned follower.

You can have up to 5 summoned spiders following you at the same time, using another spider scroll would despawn the oldest summoned spider.